Affiliation: | Department of Physics, University of Birmingham, P.O. Box 363, Birmingham BI5 2TT, United Kingdom The NET Team, Max-Planck-Institut fur Plasmaphysik, Boltzmannstrasse 2, D-8046, Garching bei Munchen, Fed. Rep. Germany |
Abstract: | Equations are given which describe the permeation rate, diffusivity and solubility of hydrogen over the range 250–600°C at pressures up to 105Pa for the 316L stainless and modified 1.4914 martensitic candidate steels proposed for the construction of the Next European Torus (NET). For heat-treated 316L steel, the permeation rates measured agreed well with previous work and did not vary significantly from specimen to specimen or from batch to batch. Measurements of the permeation rate of hydrogen and deuterium through the modified 1.4914 steel, believed to be the first made, show that the martensitic steel is significantly more permeable than the austenitic steel, by an order of magnitude at 250°C and a factor of five at 600°C. This difference could make it necessary to use permeation barriers on critical components made from the martensitic steel in order to reduce the tritium permeation rate to acceptable levels. |